MicroRNAs function as tumor suppressors or oncogenes: Aberrant expression of microRNAs in head and neck squamous cell carcinoma

MicroRNAs (miRNAs) are endogenous short non-coding RNA molecules that regulate gene expression by repressing translation or cleaving RNA transcripts in a sequence-specific manner. Bioinformatic analyses predict that miRNAs regulate more than 30% of protein coding genes. To date, 1921 human mature miRNAs have been registered in miRBase release 18.0 (http://microrna.sanger.ac.uk/). A growing body of evidence suggests that miRNAs are aberrantly expressed in many human carcinomas and that they play key roles in the initiation, development and metastasis of human cancers, including head and neck squamous cell carcinoma (HNSCC). In this review, eight genome-wide miRNA expression profiles were used to selected aberrantly expressed miRNAs (up-regulated and down-regulated miRNAs) in HNSCC clinical specimens including our miRNA profiles of hypopharyngeal and maxillary sinus squamous cell carcinoma. We discuss recent findings on the aberrant expression of miRNAs and their contribution to human HNSCC oncogenesis.